1. Field of the Invention
The present invention relates to the C-alkylation of hydroquinone or monoethers thereof, and, more especially, to such C-alkylation by vapor phase reaction with an alkanal in the presence of a solid catalyst.
2. Description of the Prior Art
Among the alkyl hydroquinones, a particularly desirable compound is methyl hydroquinone, which is used for preparing methyl hydroquinone diacetate, a valuable monomer used for the synthesis of thermotropic polymers.
A variety of processes are known to this art for preparing methyl hydroquinone. For example, U.S. Pat. No. 2,041,593 describes the hydrolysis of 4-chloro-2-methylphenol into methyl hydroquinone in an aqueous sodium medium. EP-A-1,441 describes the hydroxylation of orthocresol in hydrogen fluoride at -40.degree. C., in the presence of antimony pentafluoride. U.S. Pat. No. 4,482,756 describes the oxidation of orthocresol by oxygen, in the presence of cupric chloride in acetonitrile.